Apparatus for re-refining oil



April 12, v1938. G. x. HENSHAW v2,113,841

APPARATUS FOR RE-REFINING OIL Q Filed Dec.. 3l, 1954 2 Sheets-Sheet l April 12, 1938. G. x. HENSHAWy 2,113,841

APPARATUS FOR RE-REFINING OIL Filed Dec. 3l, 1954 2 Sheets-Sheet 2 "INVENTOR -"`Patentecl Apr. 12,1'938 uNiTfED STATES' PATENT OFFICE Y 2,113,841- APPARA'rUs yFon R- RFIMNQ on.l Gilbert X. Henshaw, Kansas City, Mo.A Application December 31, 1934', seria1'N0..7`59,919

12 claims. v(o1. '19e-1t) Q? This invention relates to a method and apparatus .for re-rening oil, particularly used lubricating oils, and Vhas, for its principal objectto restore such oils totheir original specification as 1.5 to viscosity, specic gravity, ash point, acidity, coloryand other characteristics by which good `lubricating oils are known and classified.-

- Other important objects kofthe invention are to provide a method and apparatus whereby lubri- 10 catingoils maybe re-rened atminimum cost kand tol provide for quiet and particularly safe `operation of a re-reiining system, to eliminate fire hazards, toprovide removal of alloffensive odors from the system, and to provide means for l utilizing the vacuum pump for handling the oil during its progress through the re-refming equipment.

In accomplishing these and other objects of the invention, as hereinafter pointed out, I have pro- ,7 vided improved details of structure, the preferred form of which is illustrated in the 4accompanying drawings, wherein: I

Fig. l'is a schematic `diagram of a re-reiining Y systeml embodying the features of the present in- 25 Vel'll'iOn.

Fig. 2 is a vertical sectional view throughV the heating chamber or still employed in the system.

Fig. 3 is a vertical section through the settling tank. 0 Fig. 4 is a vertical section through the lter unit of the system.

Fig. 5 is a detail section through the upper encly or the condenser in which gas, distilled fromthe lubricating oil, is condensed. I Y

35 Fig. 6 is a detail sectional View of the spray device for drawing the condensing fluid from the condenser and spraying it into the gaseous vapors drawn from thesystem.l

Referring more in detail to the drawings:

40 i designates a storage tank for containing used lubricating oil which is to be re-rened as later described, and wherein a great deal of natural settling occurs in the oil to permit foreign matter to be drawn oi as a sludge prior to delivery of the i5 cil into the re-rening system. The storage tank I includes a cylindrical wall 2 having a cone shaped bottom 3 in which the sludge is collected and drawn oil through a valve iitting 4 connected with the lowest point of the cone-shaped bottom 50 3 as illustrated in Fig. 1. The wall 2 of the tank is provided with a plurality of vertically spaced draw-off connections 5 communicating with a common lpipe 6 leading to a mixing tank l, each of the draw off connections 5 being pro-vided with 55 /valves 8 for selectively closing the flow therethrough and whereby the oil may be drawn off at anyoneof the selectedn levels.

'Ihe mining tank ,lconforms in'shape to the storage tankgiV ,in that it has a cone-shaped bottom 9 which isconnected byaipipe I0 with anair 55 supply tank fI I ,through which air from the tank I.I `is delivered forl agitatingoil containedtherein rand-for mixingthe oil with a treating agent such as fullers earth, diatomaceous earth, or

other of the various prepared puriers which are 10 no-wnmarketed for use in purifying oils and like liquids. .I 'Y

Due to the 4fact that used oils are diluted by volatile fluids, it is necessary to remove the dilution by distillation through the application of heat, which step is preferably performed prior to f admixture of the treating agent. I also nd that the oil when heated is more susceptible tothe action of the reagent Therefore, priorto addition of the purifying vand I5l being provided with suitable valves I6 and Il` to control flow therethrough as later described. The air supply pipe Ill is also provided with asimilar valve I8 toshut oi supply of compressed air to the mixing tank prior to mixing of the; purifying agent with the used oil. The pipe I3 connects a pipe I9 through'a crossover line having a valve 20 therein, and which is connected with the upper portion of the heating chamber-I2. The pipe I tis also connected with a drain pipe 2| leading from the bottom of the heating chamber through a cross over line 22; a valve 23 being located in thev drain pipe 2|. The pipe I3 is also provided with valves 24 and 25 v located on the outer respective sides of the points of connection of the pipes I 9 and 22 therewith to control flow of oil to and from the still as later described.

The heating chamber I2 may be of any suitable type,- but is` here shownas comprising a horizontally arranged cylindrical tank 26 having an electric heating element 2l extending into` the tank from one end 28 thereof in slightly spaced relation with the bottom of the tank so that the heating elementis located in the body of the oil and 40 I Y Y A the valve 31 is a T-tting 4B that is connected by above any water that may collect in the bottom thereof. r Y Y Y Y Upon heating of the oil, the volatile diluents contained thereinV are distilled and drawn off through -a pipe 29 connected with the top of the heating chamber I2. Should there be moisture entrainedwith the oil, this moisture will be driven cii in the form of steam, together with the distilled vapors.

In order toV cause movement of the oil from the mixing tank 1,/the pipe 2S is connected with a VVpipe 3G which in turn is connected to a pipe 3! through a connecting branch 32, thepipe 3| being connected with the intakeof. a pump.

33 preferably of the gear type for creating aV Vacuum in the system, theV discharge side ofthe pump being connected with a pipe 34 leading to a waste YpipeY 375. Thus, upon V-operationcf the vacuum pump, the pressure within the heating ,chamberV is brought below theratmospheric pressure so that the'air acting VonV the body of liquid in the mixing chamber causes movementthereof into the heating chamberwhen the valves I1, 24, 2D, and 35 are opened Aand the valves I6, 23, and Yare closed, the oil'being discharged from the fmixing chamber through the pipes VI 5, I3, and' I9 Y into the heating chamber. After the Ybody of oil has been' transferred into the heating chamber,

'the valve :itA that is located inrthelpipe I9 is closed to cut off communication'of ythe heating, V.chamber with the rest of the system through the Vpipe IQ. The oil is then brought to the desired temperature to cause vaporization of the volatile products kcontained in the oil which are removed through a pipe 129 upon closing a stop valveV 31 connected therein and which shuts oi direct communicaticnof the line 29 with the vacuum' pump 33. Y

Located between stop and waste valves 38 and whichV are Yconnected in the pipe 29 adjacent a pipe Y4I with'a condenserV 42 'wherein the volatile elements are passed and delivered to ajcon- The condenser 42 may be Vof,

wdensa'te'tank 43.V 'any conventional design, butfis shown as includ-V ing a vertically arranged cylindrical tankhav'- ing closed ends 44 and 45 for containing a'body of condensing fluid 45 to maintain a coil 41',V therein and which is connected in the'line 4|,1at aY suitable temperature to Vcause condensation of the 'condensible' vapors flowing therethrough. The condensing uid is delivered from a supply line 48 through a branch 1ine49 leading to'a fitting 5B that is connected with the upper end A4 of the condensing chamber. Y Y Y The fitting 50 includes va cylindrical Vbody 5I 'welded or otherwise sealed within an opening 52 inthe top of the condenser tank and having its lower endv communicating directly with Vthe interior of the tank. The upper end of the fitting,

however, is closed and connected with the branch Y pipe 49. Y

In order to deliver the condensing fluid at a point spaced below theV open end of the fitting 5B,`a tube 53 of smaller diameter than the diameter ci the fitting is sleeved therein and threaded into the upper end thereof for closed communication with the branch 49 in such a manner that the condensingfluid from the branch 49 is delivered through thetube 53 into the tank at a material distance below'the open end of the Viitting and into direct contact with the inlet end of the condenser core.

The condensing liquid is thus delivered at the Vhottest-end of the coiltol absorb heat ofthe coil The lower endlo. the coil `off through -a pipe 54 that is connected Vto a laterally extending neck 55 on the fitting 5U and which connects with a nozzle 56 inserted in the pipe 3I-leading to the vacuum pump. This construction effects Vremoval of the water by the pump at the same rate as it enters thecondenser. Since Vthe water is'drawn through the pump it acts as* af lubricating and Vcooling medium' to maintain thepump in cool'conditi-on. The pump hasV a greater capacity than that required to move'the water sol as not to interfere with theV vacuum seal for the pump.

41 connects with the upper portion of the condensate tank'through a Vpipe 51 forming a continuation of the pipe 4I so that the condensate and non--condensible va-v fpors are deliveredtogether to the. condensate tank wherethe non-condensible vapors separate and are drawn ofi through the pipe'58 connected with the pipe Sii at the pointV of connection with the piPeYSZby'aT-tting 59.V e

VThe nozzle 55 includes v-a cylindrical body membei' 60 arranged'in axial relation with the pipe 3| and with'its oppositeend connected to the pipe 54 and has a lateral connection 6I for connecting theV pipe 32. Y Y' Fixed Vconcentrically within the "nozzle body Y through whichlthe condensingV fluid is atomized under action of the vacuum pump 33 .to cause saturation of non-condensible vapors drawn from the tank 43 `before'they are delivered to the-waste pipe .35. The condensing fluid absorb's'all of the offensive odors from the vapors and 4eliminates the Vpossibility of a fire or explosion due to friction in the pump -as all of the explosive vapors are absorbedY by the condensing fluid before passing to the pump.

i f Locat'edon the respective sides of the T-tting 59 are stop valves 65 and 65 and a stop and waste valve 61 so that when the condensing portion Yof the system is in operation, the valve E6 is closedand the valve 65 isopened so that the 'noncondensible vapors are drawn off through the 'pipe 29, condenser coil 41, condensate tank 43 Yand pipe 32 'and mixed with'the water spray discharged from the orifices 64.' v

The light condensate collecting in the tank 43 may be drawn oif through acock rwhile the water or heavyV condensatewhich collects at a lower level in the tank is drawn oiffthrough a drain valve 55 connected with the bottom of the tank.

During heating of the oil, any water content thereof'isvapori'zed in the. form of steam which moves at extremely high velocity through the body of heated oil producing'violent agitating action within the still which produces a thumping Fand pounding effect within the heating chamber.

In order to overcome this difficulty, I provide for equalizing forces Yacting on the respectivesides of the body of fluids contained in the heating chamber-to slow down movement of the vapors by drawing the heat'toward the bottom of the chamber. This'is accomplished by a by-pass pipe 10 having Vits upper end connected with therpipe I9 below the valve 36 and its lower end connected rin vcommunication with the discharge end of the lower side of the body of the oil that is acting onV ythe upper side, tending to prevent violent agitation of the liquid during the heating process and to eiect a more even distribution of heat throug the fluids. After the oil has been brought to a temperature, for example 450 F., the oil is allowed to cool to a suicient degree and the stop and waste valve 38 is closed to open the line 29 to atmosphere andthe valves 23, 24 and IB are opened v to allow gravitational flow of the oil back to the mixing tank. The purifying agent isthen Vadded Cil to the oil during agitation by the jet of compressed air delivered from the tank Il when the valve I3 is opened and the valve Il closed.

Airpressure is maintained within'the tank Il by means of a compressing unit including an `air compressor 'i3 that is connected with the tank by a pipe 'lll and which is operated by a suitable prime mover, such as a motor l5.

After the oil and treating agent have been thoroughly agitated and the treating agent is 'contained in suspension in the oil, the oil is delivered to a cooling or handling tank I6 and allowed to cool to the desired temperature.

The cooling tank 'I6 is' preferably of cylindrical v shape and is connected with the mixing tank through the pipe 11 that connects with the pipe I 3.

In order to cause flow of the oil into the cooling tank, the upper portion of the cooling tank is connected by a pipe 18 with the pipe 29 wherethrough a vacuum is drawn into the cooling tank to cause lifting of the oil from the lower level of the mixing tank. f

It is thus apparent that when the valves 23, 20,

and 39 are closed and the valves Il, 24, and 25 are opened oil will be diverted from the heating chamber so that it will passrthrough the pipe 'il into the tank 76. If desired the oil may be initially elevated from the mixing tank into the heating chamber preparatory for heating by drawing the vacuum therein through the condenser 45, and through condensate tank 13 in the same manner as described in connection with drawing of the vapors from the heating chamber. With this method the valvesl 3l and 56 are left closed so that the pump draws all of the vacuum in the heating chamber through the condenser thereby withdrawing any vapors that may be in the still and condensing them for retention in the condensate tank, which vacuum is maintained throughout the distilling operations thus simplifying manipulation of the valves.

In some instances, particularly when the system is to be operated continuously, the oil, after being brought tothe desired temperature in the heating chamber, may be removed directly to the cooling tank lb, thereby releasing the heating chamber for another charge of oil from the tank i; When large volumes vof oil are to be treated, this is the most efficient method as the heating chamber is still in heated condition. However, when the heating chamber has been recharged with the second batch, the rst batch, after pren Y liminary cooling in the tank 1S is returned to the mixing tank for admixture of the treating mateN rial. After the oil has been treated it is again returned to the cooling tank for flow through the settling andltering portion of the system, as

later described. When the heated oil is to be removed from the heating chamber to the cooling tank, the vacuum in the heating chamber is admitted to the tank E6 upon opening valve 3l.

After pressures in the heating chamber and tank y 16 have approached equalization, the valves 2li *and 2i! are closed, the stop and Wastevalve 38 is opened to atmosphere and the valves 25 and 23 areopened. The pump then draws vacuum in the tank 16 through the lines 32 and 58, distillate tank 43, line 51 through condenserfcoil and linesf 4|, 29, and 'E8 to draw the oil through the lines 2l, 22 and 11 into the cooling tank. After -the oil has been transferred, the valves 23 and 25 are closed and the stopV and waste valve 33 is closed to atmosphere, which again allows a vacuum to be drawn inthe heating chamber. Then the valves 2i, 2%, and 36 are opened so that another lcharge of oil is drawn into the heating chamber from the mixing tank. Valve 36 is then closed. When the oil has cooled sufficiently, the

valve 66 being closedgthe valve 39 is opened to f atmosphere, after which the valve 82 in line 83 isopened, Vallowing the cooled oil to flow by gravity back'to" the mixing tank for admixture with the treating material. The treated oil'is then V`returned to the tank 'l5 for ilow through the settling and filtering partfof the'system now described. After the oil in the mixing chamber has been elevated to the tank 'l5 and the valves 25 and 66 are closed, the'oil Will be moved to a settling tank 'i9 through a drain lpipe 89 communicating with the lower portion of the settling tank upon opening of a valve 8l in `the pipe 8@ and closing a valve 82 in a pipe 83 that is connected with the pipe 89 and with the pipe i9 previously described, air being let into the tank by opening the stop and waste valve 39 which closes the remainderfof pipe 29.

The settling tank 19 is vertically arranged below the cooling tank and has a cone-shaped bottom 84 similar to the cone-shaped bottoms of 'the storage 'and' mixing tanks previously described.

Extending diagonally across the interior of the tank is a screen diaphragm 85 separating the tank into upper and lower compartments 86 and v81, the lower compartment 81 communicating with the drain pipe 88 and the upper compartment with a filter 89 wherein the settled oil is filtered from the treating agent.

The bottom end of the settling tank isr connected by a pipe 99 for discharge into the waste sorbing carbon, neutralizing acidic compounds,

coagulating saponiable compounds and restoring color to the oil. It is now necessary t0 draw off the treated oil and remove the treating material.

The oil may be drawn off at any selected level within the settling tank throughone of a plural-- ity of vertically spaced draw-off connections 92 which are provided with valves 93 and connected with a common pipe 94 leading to the lter 89 wherein the treating material is removed, as now to be described,

'I'he filter 89 is best illustrated in Fig. 4 and is shown as including an upper cylindrical Wall portion 95 terminating at its lower end in an inand the under side of the upper diaphragm are covered with layers Yof 'filtering cloth or paper |04, |04' and |05 respectively to cooperate with the diaphragm in retaining the filter material forming the bed |03 therebetween and to prevent foreign matter suspended in the oil under filtration from entering the filtering material.

The pipe 94 'which' delivers Vthe oil from the settling tank connects with the frusto-conical portion 91 of the filter at a point slightly above the base 98 thereof so that the Yoil Vis deliveredY under the filter Vbed for upward flow therethrough into the cylindrical portion of the filter.

Due to the outwardly and `downwardly inclined wall portion 91, it is impossible for" any of vthe solid matter contained within the oil stream to collect thereon, but it is caused to precipitate into the cone-shaped bottom 99 from where itV is drained tothe waste duct 35 through a branch pipe |00'having a valve |01 connected with the pipe 34. The settlings may `also be drained through a drain valve into another container.'V

Under certain conditions, it may be'desirable toheat the oil so that it will readily'pass through the lter bed and this may be accomplished Vby providing the inlet chamber ofthe iilter with an Velectric heating element as indicated at |08. After passing through the filter bedthe oil is entirely freed of the treating agent since this material cannot pass therethrough. Consequently, the'impurities are absorbed thereby.

Y V'After the ltered oil hascollectedlin the cylin- 1 drical portion 95 of the filter, it maybe drawn 'oilp through either one'of the'draw off pipes |09 Y and H0 upon opening of Yone of the Vvalves and H2, the pipes |09 and V|||l communicating with a common pipe V| I3 discharging into a rerened oil storage tank ||4 which is also provided with a plurality 'of vertically spaced draw oi connections H5 connected by a common pipe H9 so that the re-rerlnedY oil can b e drawn off at any one of the selected levels Vby opening the valve at the desired point of drawV off.

YThe bottom of the storage tank is provided withV a coneY shaped bottomV which is likewise connected with the pipe or the oil may' be drawn directly from the bottom of the tank through a valve ||8 connectedwith the pipe ahead of the valve ||9 therein.

In order to seat the peripheries of the screens in wedg'ing contact With the conical wall 96 to prevent passage of the filtering element therebetween, a cross barY is extended diametrically across the cylindrical wall portion of the filter at a point above the upper screen to form an abutment against which a nut |2| on a threaded rod |22 abuts. The rod |22 extends axially through the upper diaphragm'and is provided with a nut |23 and a tapered endf|2l| engagirig the upper sides of the upper and lower diaphragms respectively in opposition to the pressure applied to the rod by the nut |2 The use of the mechanical pump for handling the oil and the removal of the vapors is made being handledjby the pump.

possible by the 'water from' the condenser. This hazards and loss of vacuum in case of failure of the pump, I have provided a check valve |25 in the Vline 32 so thatY if the source of vacuum should fail or if an explosion'should occur in the pump the valve would close, holding the vacuum in the remainder of the equipment, and preventing any flash back through the pipes to the heating chamber or condensate tank.

If it is desired to usethe pump for lifting oil from one container to another the heating chamber may be operated by closing the valve |25 in the line 5l anddiverting the vapors through a pipe V|21 to the waste line 35,.water'belf1g drained from the bottom' of the'cordenser through a pipeY IES-to the pipe |21 for saturating the vapors. The ilowY of water in the pipe |28 is controlled Vby a valve |29. v f

From theforegoing, it is obvious that I have provided mechanism for re-rening lubricating ing the pump and-removing the offensive odors from the system.without contaminating the oil What I claim and desire to secure by Letters VPatent is:

l. InV an apparatus for re-rening a liquid of the. character described, a heating chamber for heating the liquid to vaporize volatile products contained'in the liquid, vacuum meansfor drawing ofi theY vapors,` a condenser element connected with the heating chamber for condensing the vapors, a condenser jacket surrounding saidV eiement,-a condensate receptacle connected with the condenser element, means connecting the vacuum means with the receptacleV to draw of Y the non-condensable vapors,'and means actuated incidental to operation o the vacuum means for withdrawing condensing liquid from said jacket and for spraying moisture into the non-condensable vapors withdrawn by said vacurun means.

2. In an apparatus for re-rening a liquid of the character described, aY heating chamber for V'heating the liquid to vaporize volatile products contained inthe liquid, vacuum means for drawing Yoff the vapors, means for equalizring pressures on Vthe upper andV lower sides of theV liquid in the heating chamber, Va condenser element connectedwith the heatingV chamber for :condensing the vapors, means conning a condensing liquid for movement in heat exchange rela- .tionwith said condenser element, a condensate Vreceptacle connected with the condenser element, means connectingV the vacuum means with the receptacle to draw o Ythe Vnon-condensable Va- V.pors,. and means actuated incidental to operasures on the upper and lower` sides of the liquid in the heating chamber, a condenserV Velement connected with the heating chamber for condensing the vapors,l means 'confining a condensing liquid for movementin heat exchange relation with said condenser element, means supplying acondensing liquid to said conning means, a condensate reeptacleconnected with the condenser element, means rconnecting the vacuum means with the receptacle to draw off the noncondensable vapors, and means actuated incidental to operation ofthe vacuum means for drawing the condensing liquid into the non-condensable vapors vwithdrawn by said vacuum Y means.

4. In an apparatus for re-rening a liquid of the character described, a mixing tank, a heating chamber connected with the mixing' tank for' Adensable vapors withdrawn by said vacuum means, and means connecting the vacuum means with the mixingtank for moving the liquid from the mixing tank to the heating chamber.

5. In an apparatus for re-rening a liquid of the character described, a mixing tank, a heating chamber connected with the mixing tank for heating the liquid to vvaporize volatile products contained in the liquid, vacuum means for drawing off the vapors, means for applying eects of said vacuum means on the upper and lower sides V,of the liquid inthe heating chamber, a conexchange relation with said condenser element,

means for, supplying a condensinguidto said conning means, a condensate condenser element connected with the receptacle to draw off the non-condensable vapors, means actuated incidental to the vacuum means for drawing the condensing liquid into the non-condensable vapors withdrawnV by said vacuum means, and

vmeans connecting the vacuum means with the mixing tank for moving the liquid to be re-refined to the heating chamber.

6. In an apparatus for re-rening a liquid of the character described, a heating chamber for heating the liquid to vaporize Vvolatile products contained in the liquid, vacuum means for drawing off the vapors, acooling tank, a conduit connecting the heating chamber with the cooling tank, a conduit connecting the cooling tank with said vacuummeans, valves in said conduits for effecting transfer of the liquid from the heating chamber to the cooling tank incidental to operation of the vacuum means andfor maintaining said Vacuum on the liquid when retained lin said cooling tank, a condenser, means connecting the condenser with the heating chamber and 'with said cooling tank, means connecting the condenser with said vacuum means. for withdrawing vapors from the `chamber and cooling vapors. ,Y 1

'7. In an apparatus for re-rening a liquid rof the character described, a heating chamber for heating. the vliquid to Vvaporize volatile products contained in the liquid, vacuum means for drawing'off the vaporsa cooling tank, a conduit connecting :theV heating chamber with the cooling tank, `a conduity connecting the cooling tank with said vacuum means,v valves in said conduits for eiecting transfer of the liquid from the heating chamber to the cooling tank incidental to operation of the vacuum means and for maintaining said Avacuum on the liquid when retained in said cooling tank, a condenser, means connecting the condenser with the,heatingchamberV and with said cooling tank, means connecting the condenser with said vacuum means for withdrawing vapors from the chamber and cooling tank through said condenser, means for introducing a non-combustible liquid into the vapors, and means for opening said conduits to atmosphere to allow transfer of the liquid under the influence of the vacuum means.

8. In an apparatus for re-rei'lning a liquid of the character described, a heating chamber for heating the liquid to VVaporize volatilerproducts contained in the liquid, a condenser, means connecting the condenser withlthe heating chamber, vacuum means for drawing off the vapors from the heating chamber .through said connecting means, means connecting the condenser with said Vacuum means, means for circulating a condensing liquid through the condenser responsive to said vacuum means to condense and cool the vapors, and means for delivering a cooling liquid to the vacuum means for direct contact-with any vapors drawn through the vacuum means which have not condensed in the condenser.

, 9. In an apparatus for re-rening a liquid of the character described, a heating chamber for heating the liquidV to vaporize volatile products contained in the liquid, a condenser, means connecting the condenser with the heating chamber,

Avacuum means for drawing on" the vapors from the heating chamber through said connecting means tothe condenser, means connecting the condenser with said vacuum means, a check valve in said last named connecting means, means for circulating a condensing iluid in heat exchange relation with the vapors moved through the condenser responsive to said vacuum means, and

means forintroducing a condensing'liquid intoV Vsaid last named connecting means for direct contact with any vapors drawn through the vacuum means which have not condensed in said condenser.

10. In an apparatus for re-refining a liquid of the character described, a heating chamber for Aheating the liquid to vaporize volatile products contained in the liquid, vacuum means for drawing off the vapors, a condenser element connected with the heating chamber for condensing the vapors,

, means for supplying a condensing liquid in heat drawing condensing liquid into the non-condene sable vapors withdrawn by'said vacuum means.

11. In an apparatus for re-rening a liquid of the character described, a tank, a heating chamber for,v heating the liquid to Vaporize volatile products contained Vin the liquid, a vacuum pump, means connecting the vacuum pump with the heating chamber for withdrawing said vaporized products, means actuated incidental to operacontained in the liquid, a vacuum pump for drawing off the vapor, means connecting the vacuum pump with the heating chamber for passage of the vapors, and means connected in said connecting means at a point ahead of the pump and actuated incidental to operation of the vacuum pump for drawing a dampening liquid directly intoy the vapors before they are drawn into the pump whereby said dampening liquid seals, lubricates and cools the pump to prevent explosion of said 1d vapors.

GILBERT X. HENSHAW. 

